Flow Separator And Flow Separator Method

Abstract

Disclosed is a flow separator, typically for use in separating liquid from gas in a flowing mixture of liquid and gas, e.g. water, oil and gas in a hydrocarbon well production fluid pipeline, the separator having a swirl generator disposed at the inlet to a cylindrical separation chamber and the separation chamber having an elongate liquid extraction slot formed along its wall, such that in operation the swirling flow centrifugally pushes the liquid towards the wall of the separation chamber to exit the separation chamber through the extraction slot into a collection chamber which may allow the return of the extracted liquid back into the main flow using a U-shaped tube.

1 . A flow separator for separating liquid from a flowing mixture of liquid and gas having:
 an inlet for the flowing mixture;   swirl promotion means;   a first outlet for separated liquid;   a second outlet for the remaining flow;   a separation chamber with an extraction aperture for extracting the liquid to be separated; and   a collection chamber communicating with the first outlet and arranged to collect the separated liquid extracted through the extraction aperture from the separation chamber;   
       wherein, in use, the swirl promotion means promotes a swirling flow of the flowing mixture in the separation chamber and an internal surface of the separation chamber guides the swirling liquid to be separated to the extraction aperture, which is located along the swirl path of the liquid to be separated. 
     
     
         2 . A flow separator according to  claim 1  wherein the inner surface of the separation chamber provides a smooth curved path for the swirling liquid to the extraction aperture. 
     
     
         3 . A flow separator according to  claim 1  or  claim 2  wherein the extraction aperture is located so as to allow the swirling liquid to exit the separation chamber substantially tangentially from the inner wall of the separation chamber. 
     
     
         4 . A flow separator according to any one of  claims 1  to  3  wherein the separation chamber has a swirl guide disposed on its inner surface to assist in promoting swirling flow of the liquid within the separation chamber. 
     
     
         5 . A flow separator according to  claim 4  wherein the swirl guide is a helical ridge or insert disposed against the internal surface of the wall of the separation chamber. 
     
     
         6 . A flow separator according to any one of  claims 1  to  5  wherein the extraction aperture is a slot, extending in a direction substantially parallel to the longitudinal axis of the separation chamber. 
     
     
         7 . A flow separator according to any one of  claims 1  to  6  wherein the extraction aperture has a face surface that is substantially aligned with the exit direction of the liquid. 
     
     
         8 . A flow separator according to any one of  claims 1  to  7  wherein the separation chamber is located within the collection chamber so that the exit direction of the liquid from the extraction aperture makes an angle of 45° or less with the tangent to the inner surface of the collection chamber. 
     
     
         9 . A flow separator according to any one of  claims 1  to  8  wherein angled guide means is provided externally of the extraction aperture to guide the exiting liquid in an axial direction along the collection chamber. 
     
     
         10 . A flow separator according to any one of  claims 1  to  9  wherein the first outlet drains the liquid from the collection chamber and communicates with the collection chamber at a location disposed in the opposite direction from the extraction aperture compared to the axial direction of flow of the liquid-gas mixture along the separation chamber. 
     
     
         11 . A flow separator according to  claim 10  wherein the first outlet communicates with a first arm of a U-tube, the second arm of the U-tube communicating with the flow downstream of the separation chamber at a liquid reintroduction point so as to reintroduce the separated liquid into the flow. 
     
     
         12 . A flow separator according to  claim 11  wherein the first outlet is at a lower level than the liquid reintroduction point. 
     
     
         13 . A flow separator according to  claim 11  or  claim 12  wherein the first arm of the U-tube has at least twice the capacity of the second arm. 
     
     
         14 . A flow separator according to any one of  claims 11  to  13  wherein the liquid drained into the first arm of the U-tube is encouraged to swirl by draining liquid swirl promoting means. 
     
     
         15 . A flow separator according to  claim 14  wherein the draining liquid swirl promotion means is a helical insert in the first arm of the U-tube. 
     
     
         16 . A flow separator according to any one of  claims 11  to  13  wherein, in use, at least a portion of the first arm is at an angle in the range from 30° to 60° to the vertical. 
     
     
         17 . A flow separator according to any one of  claims 11  to  16  wherein the apparatus includes measurement means located along the second arm or the inter-arm section of the U-tube for measuring properties of the separated liquid. 
     
     
         18 . A flow separator according to any one of  claims 11  to  17  wherein the apparatus includes one or more ports located along the second arm or the inter-arm section of the U-tube for sampling separated liquid. 
     
     
         19 . A flow separator according to any one of  claims 1  to  18  wherein the apparatus includes a measurement means located to measure the total volumetric flow rate at the inlet. 
     
     
         20 . A flow separator according to  claim 19  wherein the measurement means is a Venturi differential pressure flow meter. 
     
     
         21 . A conduit for conveying hydrocarbon well production fluid having a flow separator according to any one of  claims 1  to  20  located between an upstream portion of the conduit and a downstream portion of the conduit. 
     
     
         22 . A method of retrofitting a flow separator according to any one of  claims 1  to  20  to an existing conduit for conveying hydrocarbon well production fluid, the method including the step locating and fitting the flow separator between an upstream portion of the conduit and a downstream portion of the conduit. 
     
     
         23 . A hydrocarbon well production fluid metering system including a flow separator according to any one of  claims 1  to  20 . 
     
     
         24 . A sub-sea hydrocarbon well production fluid metering system including a flow separator according to any one of  claims 1  to  20 . 
     
     
         25 . A method for measuring the flow of a flowing mixture of liquid and gas components in a flow conduit using a flow separator, the flow separator having:
 a separation chamber;   a collection chamber communicating with the separation chamber via an extraction aperture in the wall of the separation chamber,   
       the method including promoting swirling of the flow in the separation chamber so that the liquid in the mixture is urged towards the internal surface of the separation chamber which guides the swirling liquid to the extraction aperture, located along the swirl path of the liquid to be separated. 
     
     
         26 . A method according to  claim 25  wherein the flowing mixture is a hydrocarbon well production fluid.